Artifacts belonging to legendary civil rights activist Rosa Parks have been auctioned off for a reported $4.5 million, according to a lawyer involved in the sale, the Associated Press reports.

The Howard G. Buffett Foundation, run by Howard G. Buffett, the son of billionaire investor Warren Buffett, purchased the items that once belonged to the civil rights pioneer who, in 1955, refused to give up her bus seat to a white man in Montgomery, Ala.

The items, which include Parks' Presidential Medal of Freedom and a postcard signed by Martin Luther King Jr., along with personal papers, notes, "letters from presidents, and various awards and honorary doctorates," were purchased on Aug. 20, according to the Chicago Tribune.

"For lack of a better term, she was a pack rat," Arlan Ettinger, president of Guernsey's auction house in New York, which housed most of Parks' belongings, told the Chicago Tribune. "She had retained many things from her long and rich life."

Howard Buffett would only confirm to AP that the purchase had taken place but would not discuss the terms of the sale. However, Lawrence Pepper, a lawyer for Parks' heirs, told AP that the sale was for $4.5 million and noted that 12.5 percent is paid to the auction house for brokering the deal.

Parks' relatives will receive 20 percent of the proceeds from the sale, and the remaining balance will go to the Rosa & Raymond Parks Institute for Self Development in Detroit, according to AP.